1. Technical Field
The invention relates to tubular elements of chrome-nickel stainless steel designed to be used in the high pressure and high temperature water in water cooled and moderated nuclear reactors.
In such reactors the cooling water frequently contains boron products and is in contact with tubular elements some of which are frequently slidingly moved within and along guides on which they rub. This occurs in particular with stainless steel sleeves of reactivity control rod clusters. To control the reactivity of the reactor, the control rods are moved along guide tubes provided in the fuel assemblies and along guides placed in the upper internals of the reactor. The frequency and the amplitude of the movements of certain rods, particularly when the reactor is used in the "load follower" mode are such that it has often been necessary to systematically replace a certain number of clusters on each core reloading.
2. Prior Art
It has already been proposed to deposit a coating on the outer surface of tubular elements subject to friction to reduce the wear thereof. Electrolytic platings of hard chromium and chemical platings of nickel have already been produced. Electrolytic chromium platings are fragile. Chemically deposited nickel may contaminate the primary circuit of the reactor. Coatings containing chromium carbide to which a nickel-chromium bonding alloy is added have poor behavior under irradiation.